This application claims the priority benefit of Taiwan application serial no. 89115370, filed Jul. 31, 2000.
1. Field of the Invention
The invention relates in general to an optical recording medium and a method for fabricating the same. More particularly, this invention relates to an optical recording medium having a read only data region and a writable data region and the method for fabricating the same.
2. Description of the Related Art
As the multimedia has been widely and commonly applied, many data carried by the multimedia contain massive text, sound and image information. Consequently, development of data recording and storing media has been concentrated on high storage density and access speed. Since the compact disc has the advantages such as high storage density, compact volume, long duration, low cost, high compatibility and low fault rate, it has been the leading recording medium for portable optical data storage.
FIG. 1 shows a top view of a transparent substrate 12 of conventional compact disc 10. FIG. 2 is a cross sectional view showing the local structure of the compact disc 10. In FIG. 1, the transparent substrate 12 comprises an opening 14 at the center thereof, and pre-pits 16 spirally distributing on the transparent substrate 12. The pre-pits 16 contain the digital data that the compact disc stores. In FIG. 2, a reflecting layer 18 is formed on the transparent substrate 12 to reflect a laser light beam emitted from an optical reading/writing head 24. A protection layer 20 is formed on the reflecting layer 18 to avoid damage on the recorded data in the compact disc 10 by the ambient. The transparent substrate 12 is typically made of polycarbonate, and the reflecting layer 18 is typically made of aluminum (Al), copper (Cu), gold (Au), silver (Ag) or platinum (Pt) or the alloy for any of the above material.
The laser light beam 26 transmits through the transparent substrate 12 to shine on the reflecting layer 18. The laser light beam 26 is then reflected to a light detector by the reflecting layer 18 to access the recorded data in the compact disc 10. As the recorded data are stored in a form of the pre-pits 16 on the transparent substrate 12, the user can only read the stored data using a compact disc drive without being able to record new data in the compact disc 10. When the data to be recorded is relevant to the data stored in the compact disc 10, the user must record such data into another compact disc. The causes great inconvenience in data access for the users.
The invention provides an optical recording medium and the method for fabrication the same to resolve the problems occurring in the conventional structure and method.
A read only data region is formed on a transparent substrate. A writable/readable data region and a content recording region are further formed on the transparent substrate. The read only data region is used to store a pre-recording data which can only be read, but cannot be rewritten. The data stored in the writable/readable data region can be rewritten and read as required. The content recording region is to record the initial address information for the recorded data and recording regions of the read only data region as well as the initial address information for the recorded data and recording regions of the writable/readable data region. The recording data region comprises a recording layer made of derivatives of cyanine dye, phthalocyanine dye, or azo dye. Or alternatively, the recording layer is made of an alloy containing tellurium (Te), antimony (Sb), or an alloy containing indium (In), silver (Ag), antimony or tellurium.
Since the above optical recording medium comprises a read only data region and a writable/readable data region, the inconvenience for data access in the conventional structure is resolved. The read only data region provides the user to read a prerecording data only. The writable/read data region enable the user to write and read the data relative to the pre-recording data without storing the relative data into another optical recording medium.
Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.